Outbreaks of cockroaches, possums, birds and insects at major hospitals have been revealed after two deaths prompted a sweeping maintenance review of hospital infrastructure.

The snap investigation in NSW uncovered incidents involving pests and fungus, dating back more than a decade, which were never reported.

It followed the deaths of two patients from fungal infections linked to construction work at Royal Prince Alfred Hospital in Sydney.

Six patients in the transplant ward developed infections between October and December last year, possibly the result of Aspergillus, a common mould found in soil, dust and damp environments.